1991941940 has 12 divisors (see below), whose sum is σ = 4183078116. Its totient is φ = 796776768.

The previous prime is 1991941873. The next prime is 1991941943. The reversal of 1991941940 is 491491991.

It can be written as a sum of positive squares in 2 ways, for example, as 906371236 + 1085570704 = 30106^2 + 32948^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991941943) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 49798529 + ... + 49798568.

It is an arithmetic number, because the mean of its divisors is an integer number (348589843).

Almost surely, 2^1991941940 is an apocalyptic number.

1991941940 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1991941940 is an abundant number, since it is smaller than the sum of its proper divisors (2191136176).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1991941940 is a wasteful number, since it uses less digits than its factorization.

1991941940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99597106 (or 99597104 counting only the distinct ones).

The product of its (nonzero) digits is 104976, while the sum is 47.

The square root of 1991941940 is about 44631.1767714005. The cubic root of 1991941940 is about 1258.2266857361.

The spelling of 1991941940 in words is "one billion, nine hundred ninety-one million, nine hundred forty-one thousand, nine hundred forty".